a disturbance in which individuals feel a loss of control after eating only a small amount of food and recurrently vomit up or otherwise expel their meals. It is differentiated from bulimia nervosa by the absence of binging. Studies indicate that purging disorder affects between 1.1% and 5.3% of women in their lifetimes and that the typical age of onset is late adolescence (18–20 years old). The condition is associated with a greater release of the hormone cholecystokinin, which controls feelings of fullness, and lower levels of the protein leptin, which conveys information about body-fat levels. [originally described in 2005 by clinical psychologist Pamela K. Keel and colleagues]